Background. Swedish wildfires are handled by multipurpose municipal rescue services, raising questions about how non-specialist incident commanders (ICs) perceive and interpret wildfire behaviour. Aims. Elucidating ICs' interpretations of fire behaviour, fuel complexes, weather, landscape structure and the role of these in tactical decisions. Methods. We exposed Swedish ICs to questionnaires and tabletop exercises for different standardised fire scenarios. Key results. Despite minimal formal wildfire training, ICs showed reasonable consensus in rating of fuels, fire behaviour, hose-lay production rates, etc. Tactics were to access the fire from the nearest road with hose-line laid from the engine and water ferried on trucks. In a scenario where initial attack failed, they typically fell back to roads, without burning off. This indicates a fundamental flaw in tactics employed for high-intensity fires, which easily breach forestry roads, and invite outflanking. Conclusions. The IC wildfire knowledge is built on personal and group experience rather than formal education. We found reasonable competence, despite the organisations being designed primarily for other purposes. However, tactical understanding of complex, large incidents was poor. IC training should emphasise potential hazards of such incidents to enhance group competence despite their low frequency. Implications. Standardised tabletop exercises can provide insight into decision-making of ICs that is otherwise hidden.

Unlike most regions with high-intensity wildfire potential, Sweden lacks specialized wildfire suppression organization. Instead, wildfire suppression is handled by highly decentralized and multitask municipal rescue services. This prompts the question how the incident commanders (ICs) perceive and interpret variation in fire behaviour and how they respond to wildfire incidents with regard to dispatching for initial attack and selecting tactics. To elucidate this, we exposed a spectrum of Swedish ICs to a questionnaire and round-table-exercises of different fire scenarios. The informants had on average 13 years of experience as incident commanders and had on average managed 6 wildfires over the last 5 years. Despite minimal formal wildfire training the respondents showed reasonable consensus in rating of fire behaviour in response to fuels and weather, suggesting that their knowledge was built on personal and group experience. Likewise, they gave estimates on rate of production of hose-lays similar to published expert assessments from Canada. When exposed to a spectrum of fire scenarios, resource dimensioning by ICs was linearly related to the Canadian FWI-index, although most organizations did not have any preordained schemas or rules of initial dispatching resources to guide them. Tactics employed were based mainly on accessing the fire from the nearest road and using direct attack with hose-line laid from the engine and water ferried on trucks. In a scenario where initial attack failed, suppression crews typically fell back on roads, which however would be breached by intense fire, and which also exposed the operation to risk of being outflanked. This response was in fact similar to that employed during a 2014 catastrophic wildfire in central Sweden and may indicate a fundamental flaw in tactics employed for large and intense fires. The present structure of the Swedish wildfire suppression system developed during the second half of the 1900s and depends on rapid access to the fire by a relatively small number of firefighters. The study suggests a relatively high capacity for suppressing forest fires, despite that the organization is primarily rigged for other purposes and that ICs have minimal formal training in this area. Climate change-scenarios suggest longer fire season and more risk days in parts of the country, but the future wildfire scene may be even more sensitive to de-population and diminishing economic resources in heavily forested regions of the country.